Process for separating gel particles



Jan. 19, 1954 J. w. PAYNE PROCESS FOR SEPARATING GEL PARTICLES 2 Shets-Sheet l Filed Jan. 5l, 1952 n n n n n u u u nmnn n JNVENTOR. faf Kayne' /1 TTURNEY Jan. 19, 1954 J. W. PAYN E PROCESS FORv SEPARATING GEL PARTICLES 2 Sheets-Sheet 2 Patented Jan. 19, 61954 2,666,524

Jh'np W: Pa'naf Woodbury; J., assignorto Socon'y-'Va'cuunt Oil Company, Incorporated',- a

corporation of New York Aliidafor Ja'y 31, 1952; serial No. 269,161

ser admitted in s6 @drained iay' be" washed. b heat treated, or oth e' with @te s claims: (o1. sost-i195 One of the difliculties encountered in the 'fori mation of the above-described spheroidal gel particles has beenthe large loss of particles due to breakage of the beads with resultant production of gel nes and' irregularly 'shaped pieces of gel. Such breakage is caused primarily by shattering of the desired gelv particles during the drying operation.l This shattering apparently results' from internal *stresses` Which develop' Within thespheroidal particles as' the liquid phase is removed. While various methods have'beenv proposed for reducing the extent of gel breakage duringthe drying and' tempering operations,- some breakage is almost invariably encountered ieormnercial operation due either to thel aforernentionediinternal stresses or to fracture vand attrition' of the dry gel" beads upon physical c on'` tact with onek another. The resultant' gel fines and` irregularly shapedpieees of gel are' necessarily' removedfr'oin the desired' vspheroidal"gel4 particles before the latter can be employed for their intended purpose. r

Onenietld hretoforefused'lfor separatirigithe finished spheroidalE gel beads from a mixture of the*samewith*brokenv beads has been to eonduct the vgel product `to'aj scre'enrigunit of r mesh sizesuch thatthev glnes' and broken pieces ot gel pass` through the screen While the bea'dsarev retained onthe screen. Such method in prac'-I 'tice'has' beenv found to'v have several vdisadvantages.V Thus, additional" bead breakage occurs on thescreen duetoalgrindingeiect exerted on the Whole`v` beadsb'yv4 the ne'sand broken beads already presenti' in` theV mixture" undergoing sepa-t ration Considerable diculties are also caused by'uscr'euerijl plugging and fouling, whichr necessif tates periodic brushing o fj the* screen.` `l I Euithermore;y specialitype screens 'lare'required' for' eff-v. fecting thefdes'iredjseparation :sincecoriyent'ional s'quarjrneshscree sfbecorne fouled'very quickly With beads which;jan/ 1' into @the screen' openings andarefextrfengely' diflcult'to dislodgeeve'n with-` frequentbrushing. v A n f l spherdal sl'fapejf"traverseA longer" trajectories than the irregularly shaped broken pieces of gel and gel fines admixed therewith. The whole gel beads are thus separated from the broken `beads by collecting the same in different recepand nes resulting from breakage of the whole beads. i

The selection of whole beads may be made increasingly sensitive by passing the mixture of whole and broken beads undergoing separation through a plurality of the above-described selector operations. Since imperfection in sphericity can lead to some spread of trajectories, it will at times occur that whole beads will not travel far enough to be deposited in the receptacle or chute most remote from the inclined dropping base. The probability that, in a second dropping of the same particles, a similar line of trajectory would be followed is extremely small, however. In fact, to a good approximation, assumng the probability of being improperly selected in one selector operation is l per cent, then the probability of being selected improperly a second successive time would be only one per cent. It is believed evident that a selection to a high degree of almost any desired extent may be realized by having a larger number of successive selector operations. Thus, in order to separate the desired whole beads with greater refinement or to reduce error, the procedure generally need only be repeated a multiple number of times and in each operation only the particles having the outermost trajectories selected.

The invention may be further understood by reference to the attached drawings wherein:

Figure 1 is an illustration of a simple embodiment of the invention;

Figure 2 is an elevational view partly in section illustrating suitable apparatus for accomplishing a continuous selective process employing principles of the invention;

Figure 3 is an elevational view partly in section showing an alternate apparatus set-up suitable for the continuous selective operation.

Figure 4 is an elevational view partly in section illustrating an apparatus designed for a plurality of successive selector operations.

Referring particularly to Figure l, a mixture of whole and broken gel beads, all of which have undergone substantially complete shrinkage, are dropped from a moving belt l0 onto an inclined base ll. The whole beads, due to their spheroidal shape, rebound from the inclined plate in a line of greater trajectory, whereas the broken irregularly shaped beads rebound from the inclined plate in a line of lesser trajectory. The particles of lesser trajectory are collected in a receptacle i2 adjacent 'to the inclinedV base and the whole beads of greater trajectory, collected in receptacle I3, remote from the inclined base.

Turning now to Figure 2, a dried mixture of whole and broken gel beads are conducted by means of trough i4 onto an endless moving belt i5 which passes through chamber IE. The gel particles continue passage along the belt and drop from the end thereof onto inclined base `Il of a suiiiciently hard material as to cause the particles to rebound. The whole beads rebound with a greater trajectory into chute I8 and pass from the apparatus through outlet conduit it. llhe irregularly shaped broken beads and gel onto an endless moving belt 2l.

4 fines rebound with a lesser trajectory into chute 20. The latter particles pass through conduit 2l and enter a'bucket type elevator 22. The particles are then lifted from the point of entrance to an elevated point at the top of the elevator. From said elevated point, the particles are dumped from theA elevator buckets through conduit 23 which serves to recycle the particles passing therethrough to the endless moving belt i5. This continuous process, as pointed out above, serves to eliminate any spread of trajectories due to imperfection in the spherical form of the particles. To prevent accumulation of broken gel beads and fines in the apparatus, these are removed at intervals through outlet 24.

Referring to Figure 3, a dried mixture of whole and broken gel beads' are led through conduit 2S The mixture passes along the moving belt and the particles drop from the end thereof onto an inclined plate 28. Whole spheroidal gel particles rebound from the inclined plate in a line of greater trajectory and fall into receptacle 29. The irregularly shaped broken gel particles rebound in a line of lesser trajectory and fall into receptacle 30. The latter particles pass from receptacle 3G onto a second endless moving belt 3l, moving in a direction opposite to that of the first belt. The particles pass along the second moving belt and fall from the end thereof into a receptacle 32. The particles then pass through conduit 33 into a gas lift chamber 34. A gas, such as air, steam, or other gas inert to the particles, is conducted through pipe 35 and serves to lift the gel particles in chamber 34 vertically upward. The particles thereafter pass from chamber 34 through outlet conduit 35i and are thus recycled onto moving belt 2l. A vapor seal is maintained in conduit 33 by passage of a gas through pipe 3l. This gas will generally be the same gas as that conducted through pipe 35. Surrounding the two endless belts is a Wall 38 defining a chamber. The accumulation of broken gel beads andv nes in the apparatus is prevented by periodic removal thereof through outlet 39.

In the apparatus of Figure 4, a mixture of whole 4andfbroken gel beads is conducted by means of trough 4I onto an endless moving belt 42. The particles, comprising whole spheroidal beads and irregularly shaped broken beads and gel fines, pass along the surface of the endless belt and drop from the end thereof onto an inclined base 43. The gel spheroids rebound from said base in a line of greater trajectory and fall into receptacle 44. The remaining particles, comprising mostly gel fines and broken beads, rebound from base 43 in a line of lesser trajecvtory and fall in receptacle 45. The latter particles are conducted through conduit 4S and pass onto the surface of a second moving belt 41 which is moving in adirection opposite to that of the rst belt. The particles move along the second moving belt and drop from the end thereof onto a second inclinedV base 48. Whole beads present in the mixture rebound lfrom base 48 in a line of greater trajectory vand fall' into receptacle 4S. The remainder of't'he'particles, made up for the greater part ofV irregularly shaped broken gel beads and nes, rebound fromplate 4Sv in a line of lesser trajectoryand fall into receptacle 5i). The latter particles pass through conduit 5I onto the surface of a third endless moving belt 52 moving in a direction opposite to that of the second belt. The particles pass along the surf-ace vof the third moving belt and vdrop from ther end thereof n'rda third icld has@ 5 3..- Registreren? beads presenti in lthej mixture rebound from base 3 in aline of jgreater'trajfectory into receptacle 54. Broken' vbeads' and -gel fines rebound-from base 5 3 in alineo'f lesser trajectory-and fall into receptacle 55,'from which theyl are conducted to storage through conduit 56. The desiredwhole gel beads are removed from the outermostreceptacles and pass Vinto conduits 5Ta`nd`58. The endless belts are enclosed withinfa chamber 5g. It will beV understood that the number-'of' end-V lessmoving belts and inclined bases employed will depend upon the extent of desired sep-ara# ti'on'of the whole and vbreiten gel beads being processed. e venient number of endless-'belts-and inclined bases maybe employed in achieving the-'objects of the invention. Y Y

The following example will serve to illustrate the process of the invention without limiting the same: f

Examplev A silica-alumina hydrosol was prepared by mixing 1.00 volume of a solution of sodium silicate containing`l57.0` grams'of SiOz per .liter with 1.00y volume of a solution containing 39.79 grams of aluminum sulfate and 30.51, grams of 'sulfuric acid per liter. The resulting 'colloidal solution wasejected from a nozzle in the form of globules into aY column of gas oil, the depth of which was 8 feet. The globules of solution fell through the oil and gelled before passing into alayer of water located beneath the oil.. The, time of gelationfor the concentrations and proportions of reactants given above was about-Seconds The spheroidal particles of gel were conducted` out of the bottom of the column intov a 'stream ofwater and, on removal from the Water, base-exchanged with an aqueous solution of aluminum sulfate and waterwashed. The pellets were then slowly and uniformly dried in superheated steam at about 300 F. and thereafter calcined at about 1300" F. to yield particles having a size of between about 4 and about 20 mesh.

The resulting hard, glassy spheroidal gel beads contaminated with gel lines and irregularly shaped particles resulting from breakage of the beads were then dropped from a height of 21.5 inches in a vertical line onto an inclined metal plate. The angle of inclination of the metal plate was 22.5 with the horizontal. The dropped particles rebounded from the surface of the inclined metal plate. The Whole gel beads rebounded in a line of greater trajectory and were collected in a tray remote from the inclined metal plate. The irregularly shaped broken beads rebounded in a line of lesser trajectory and were collected in a tray adjacent to the inclined metal plate. A baille 11.5 inches in height separated the two trays. All particles which rebounded a distance of at least 21.5 inches from the point of dropping were collected in the tray remote from the metal plate. In this single step selection process, about 38 per cent of all the whole beads present were collected in the outermost tray. The remaining 62 per cent of Whole beads, due to imperfection in sphericity or collision with other beads, fell short of the outermost tray and were collected in the tray adjacent to the inclined glass plate, as were the irregularly shaped broken beads and gel fines.

It will be evident from the foregoing example that the procedure of this invention affords an effective means for selectively separating a mixture of whole and broken spheroidal inorganic It is contemplated' that'. anyl -conl.

gel particles. f- 'It is? to bel noted that the whole and brokengel'beads undergoing 'separation have previously been subjected to identical drying conditions and that they consequently are substantial'ly identical with' Aregard to water content and degree of hardness. It is 'essential rfor purposes of the-present 'invention that themiXtu-re of gel p'articles'under'geing separation be characterized by a substantially-identical degree ofhardness sincethe. elasticity property -relied upon herein for 'separationi's directly related to the liquid content A and consequentlyv the gelY hardness. Should the mixture being separated by the present-process comprise gel'` particles of varyingA degrees of liquid content or hardness, it isl apparent that the instant method forseparatingv whole and broken gel beads would become unduly involved and 'cumbersome since vvv-holek beads having ditfer'ent. degrees of liquid content or hardness would themselves have varying trajectories upon dropping the same 'on' an inclined plate as described above. Under such conditions, irregularly shaped broken gel beads and softer whole beads of somewhat' greater moisture content might very well have the same.- trajectories upon dropping and consequentlybe mcapable of separation by this means. Itis accordingly essential for successful operationof the instant process; that the gel particles.4 undergoing separation. be characterized by a.. substantially identical degree of hardness.

While the particles will be4 dropped. generally in a. vertical line onto the inclined base, ity is within the purview .of invention tov vary the angle of incidence, between, the path of the falling-particles and the plane of the. inclined base. vlhus, iorgrazmg incidence, the particles will rebound considerably less than for' angles near to the. perpendicular. The inclined; base is made of a material of suiiicient hardness as to cause the gel particles falling thereon to rebound. Generally, the inclined base will .be made of metal, glass, porcelain, or any other material having the requisite hardness. The angle of inclination of the base likewise may be varied, depending on the nature of the inorganic gel particles being separated. Generally, however, the

angle of inclination of the inclined base will be between about 5 and about 45 with the horizontal.

Separation of the mixture of whole and broken.

gel beads, in accordance with the instant process, may be carried out on the dried beads beforey tempering or, as will generally be the case, the` mixture after tempering will be subjected to the described separation with collection of the 1in-- veach of which is characterized by a substantially identical degree of hardness, which comprises dropping a mixture of said particles from a point of predetermined height onto an inclined base of su'icient hardness as to cause the particles to rebound, collecting the particles of lesser traectory in one receptacle and the particles of greater trajectory in a second receptacle and recycling said particles of lesser trajectory to said point of dropping.

3. A continuousv process for separating'a mixture of Whole and broken spheroidal bead-like gel particles, each of which is characterized by a substantially identical degree of hardness, which comprises continuously dropping a mixture of said particles from a point of predetermined height onto an inclined base of sufficient hardness as to cause the particles to rebound, collecting the particles of lesser trajectory in one receptacle and the particles of greater trajectory in a second receptacle, conducting said particles of lesser trajectory to a vertical gas lift, thereby causing the gel particles contained therein to rise to an elevated point in said lift and recycling said particles from'said elevated point to said point of dropping.

4. A continuous process for separating a mixture of whole and broken spherodal bead-like gel particles, each of f which is characterized by a substantially identical degree of hardness, which comprises dropping a mixture of -said particles from a predetermined height onto an inclined base of sufficient hardness as to cause the particles to rebound,'collecting the particles of lesser trajectory in one receptacle and the particles of greater trajectory in a second receptacle and thereafter dropping said particles of lesser trajectory from a predetermined height onto a hard, inclined base a multiple number of times to attain selective separation thereof.

5. A method for separating a mixture made up of gel spheroids and irregularly shaped gel fragments of smaller particle size, which comprises dropping such mixture, all particles of which have dried to a substantiallyV identical liquid cond tent, from a predetermined height onto an in-v clined base of sufficient hardness as to cause the particles to rebound and collecting the particles of lesser trajectory in one receptacle and the particles of greater trajectory in a second receptacle.

6. A method for separating a mixture made up of gel spheroids and irregularly shaped gel fragments of smaller particle size, which comprises dropping such mixture, al1 particles of which have dried and tempered to a substantially identical liquid content, from a predetermined height onto an inclined base of sun'icient hardness as to cause the particles to rebound and collecting the particles of lesser trajectory in one receptacle and the particles of greater trajectory in a second receptacle.

JOHN W. PAYNE.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 159,853 Stamford Feb. 16, 1875 643,912 Schlink Feb. 20, 1900 873,326 Pearce Dec. 10, 1907 1,155,292 Torrey Sept. 28, 1915 1,704,056 Nearing Mar. 5, 1929 2,260,095 Stone Oct. 21, 1941 2,304,554 Dixon Dec. 8, 1942 2,607,482 Weisz Aug. 19, 1952 FOREIGN PATENTS Number Country Date 98,459 Germany July v28, 1898 5,783 Great Britain of 1899 656,038 France Dec. 24, 1928 

